where is the type field of libc struct Dir documented? In source I found a compare of field type with the char 'M'. Where can I loop up what 'M' means?
It's the Unicode character used to identify the device driver within a kernel,
and are part of the device driver's Dev value. Only a few have any sort of global
significance, and even that's probably a mistake.
cat /dev/drivers
for the map currently in use. /sys/src/9/port/master tries to keep track of them,
but as you'll see some characters are used for several devices (not in use simultaneously in the same kernel)